Image sensors including pixel groups and electronic devices including image sensors

ABSTRACT

An image sensor includes first photodiodes sharing a first node that is connected to a first capacitor, second photodiodes sharing a second node that is connected to a second capacitor, a common transistor configured to selectively connect a third node to a pixel voltage node, the third node connected to a third capacitor, a first reset transistor that may selectively connect the first node to the third node, and a second reset transistor that may selectively connect the second node to the third node. The first reset transistor and the second reset transistor may electrically connect the first node, the second node, and the third node to each other according to an operation of the first reset transistor and the second reset transistor. The common transistor is configured to reset the third node to the pixel voltage according to an operation of the common transistor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/841,796, filed Apr. 7, 2020, which claims the benefit of KoreanPatent Application No. 10-2019-0041057, filed on Apr. 8, 2019, in theKorean Intellectual Property Office, the disclosure of each of which isincorporated herein in its entirety by reference.

BACKGROUND

The inventive concepts relate to image sensors, and more particularly,to image sensors including pixel groups.

Image sensors may convert one or more optical signals received at theimage sensors, where the one or more optical signals may includeinformation associated with one or more images of one or more subjects,into one or more electrical signals. Charge-coupled device (CCD) imagesensors and complementary metal oxide semiconductor (CMOS) image sensorsare widely used as image sensors. Recently, in accordance to thedevelopment of the computer industry and the communication industry, thedemand for image sensors having improved performance in variouselectronic devices such as digital cameras, camcorders, personalcommunication systems (PCSs), game devices, security cameras, medicalmicro cameras, mobile phones, or the like is increasing.

Image sensors may have increased resolution based on including a largerquantity of pixels. A plurality of photodiodes (PDs) may share one nodeto a larger number (e.g., quantity) of pixels. In accordance to thephysical sizes of other elements (for example, a plurality oftransistors, a capacitor, and a metal contact connecting the pluralityof transistors and the capacitor) and the limitation of the design rule,the miniaturization of the pixels is difficult.

SUMMARY

The inventive concepts provide image sensors that have reducedcomplexity of a layout that more efficiently utilize chip space in theimage sensors and are configured to support a dual conversion gain (DCG)function even when small-sized pixels are included in the image sensors.Accordingly, compactness of the image sensors having said reducedcomplexity may be improved, thereby enabling the image sensors to beincluded in smaller devices and/or to enable additional elements to beincluded in space, in the devices, that is made available due to theimproved compactness of the image sensors, thereby enabling the devicesto have increased functionality, performance, etc.

According to some example embodiments, an image sensor may include aplurality of first photodiodes sharing a first node, the first nodeconnected to a first capacitor, a plurality of second photodiodessharing a second node, the second node connected to a second capacitor,a common transistor configured to selectively connect a third node to apixel voltage node, the third node connected to a third capacitor, afirst reset transistor configured to selectively connect the first nodeto the third node, and a second reset transistor configured toselectively connect the second node to the third node. The first resettransistor and the second reset transistor may be collectivelyconfigured to selectively electrically connect the first node, thesecond node, and the third node to each other according to an operationof the first reset transistor and the second reset transistor. Thecommon transistor may be configured to reset the third node to a pixelvoltage according to an operation of the common transistor.

According to some example embodiments, an image sensor may include aplurality of first photodiodes sharing a first node, the first nodeconnected to a first capacitor, a plurality of second photodiodessharing a second node, the second node connected to a second capacitor,a first reset transistor configured to selectively connect the firstnode to the second node, a second reset transistor configured toselectively connect the second node to a third node, and a commontransistor configured to selectively connect the third node to a pixelvoltage node. The third node may include an electrical connection with athird capacitor.

According to some example embodiments, an electronic device may includean image sensor. The image sensor may include a plurality of firstphotodiodes sharing a first node, the first node connected to a firstcapacitor, a plurality of second photodiodes sharing a second node, thesecond node connected to a second capacitor, a common transistorconfigured to selectively connect a third node to a pixel voltage node,the third node connected to a third capacitor, a first reset transistorconfigured to selectively connect the first node to the third node, anda second reset transistor configured to selectively connect the secondnode to the third node. The first reset transistor and the second resettransistor may be collectively configured to selectively electricallyconnect first node, the second node, and the third node to each otheraccording to an operation of the first reset transistor and the secondreset transistor. The common transistor may be configured to reset thethird node to a pixel voltage according to an operation of the commontransistor.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the inventive concepts will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 illustrates an example structure of a digital imaging deviceaccording to some example embodiments of the inventive concepts;

FIG. 2 is a block diagram of a configuration of an image sensoraccording to some example embodiments of the inventive concepts;

FIGS. 3A and 3B respectively illustrate a circuit diagram and a layoutof a first pixel group and a second pixel group;

FIG. 4 is a circuit diagram in which the first pixel group and thesecond pixel group share transistors and voltage nodes according to someexample embodiments of the inventive concepts;

FIGS. 5A and 5B respectively illustrate a circuit diagram and a layoutin which a 3-way transistor is used according to some exampleembodiments of the inventive concepts;

FIGS. 6A and 6B respectively illustrate a circuit diagram and a layoutin which a 4-way transistor is used according to some exampleembodiments of the inventive concepts;

FIGS. 7A and 7B respectively illustrate a circuit diagram and a layoutin which an additional capacitor is connected to a 4-way transistoraccording to some example embodiments of the inventive concepts;

FIGS. 8A and 8B respectively illustrate a circuit diagram in which afirst pixel group and a second pixel group share transistors and voltagenodes according to some example embodiments of the inventive concepts;

FIGS. 9A and 9B respectively illustrate a circuit diagram in which afirst pixel group and a second pixel group share transistors and voltagenodes according to some example embodiments of the inventive concepts;

FIGS. 10A and 10B respectively illustrate a circuit diagram and a layoutin which an additional capacitor is connected according to some exampleembodiments of the inventive concepts; and

FIG. 11 is a block diagram of a computing system including an imagesensor according to some example embodiments of the inventive concepts.

DETAILED DESCRIPTION

Hereinafter, some example embodiments of the inventive concepts will nowbe described in detail with reference to the accompanying drawings.

FIG. 1 illustrates an example structure of a digital imaging device 1000according to some example embodiments.

The digital imaging device 1000 according to some example embodimentsmay include an image generator 1100, an image sensor 100, and aprocessor 1200.

An overall operation of the digital image generator 1000 may becontrolled by the processor 1200. The processor 1200 may provide (e.g.,transmit) a control signal to a lens driver 1120, a diaphragm driver1140, a controller 120, or the like to operate each element.

The processor 1200 may include processing circuitry such as hardwareincluding logic circuits; a hardware/software combination such as aprocessor executing software; or a combination thereof. For example, theprocessing circuitry more specifically may include, but is not limitedto, a central processing unit (CPU), an arithmetic logic unit (ALU), adigital signal processor, a microcomputer, a field programmable gatearray (FPGA), a System-on-Chip (SoC), a programmable logic unit, amicroprocessor, application-specific integrated circuit (ASIC), etc.

The image generator 1100 is an element (e.g., device) configured toreceive light 2001 (e.g., incident light from an exterior of the digitalimaging device 1000) and may include a lens 1110, the lens driver 1120,a diaphragm 1130, and the diaphragm driver 1140. The lens 1110 mayinclude a plurality of lenses.

The lens driver 1120 may adjust a position of the lens 1110 according tothe control signal provided from the processor 1200. The lens driver1120 may move the lens 1110 in a direction in which a distance from anobject 2000 increases or decreases. Therefore, the distance between thelens 1110 and the object 2000 may be adjusted. A focus with respect tothe object 2000 may be taken or blurred depending on the position of thelens 1110.

The image sensor 100 may convert incident light 2001 into an imagesignal. The image sensor 100 may include a pixel array 110, thecontroller 120 and a signal processor 130. An optical signal through thelens 1110 and the diaphragm 1130 may reach a light-receiving surface ofthe pixel array 110 and form an image of a subject.

The controller 120 and the signal processor 130 may each includeprocessing circuitry such as hardware including logic circuits; ahardware/software combination such as a processor executing software; ora combination thereof. For example, the processing circuitry morespecifically may include, but is not limited to, a central processingunit (CPU), an arithmetic logic unit (ALU), a digital signal processor,a microcomputer, a field programmable gate array (FPGA), aSystem-on-Chip (SoC), a programmable logic unit, a microprocessor,application-specific integrated circuit (ASIC), etc.

The pixel array 110 may be a complementary metal oxide semiconductorimage sensor (CIS) converting an optical signal into an electricalsignal. The sensitivity of the pixel array 110 may be adjusted by thecontroller 120. For example, the pixel array 110 may include a pixelgroup supporting a dual conversion gain (DCG).

According to some example embodiments, the processor 1200 may usesurrounding luminance information to determine to operate in a lowconversion gain (LCG) mode or a high conversion gain (HCG) mode. Forexample, when the surrounding (e.g., ambient environment external to thedigital imaging device 1000) is bright, an operation is performed in theLCG mode. When the surrounding is dark, an operation is performed in theHCG mode such that an ability to identify objects may be improved.

According to some example embodiments, the processor 1200 may reducenoise of an input signal and perform an image signal processing forimproving image quality such as gamma correction, color filter arrayinterpolation, color matrix, color correction, color enhancement, or thelike. In addition, image data generated by processing the image signalfor improving the image quality may be compressed to generate an imagefile or the image data may be recovered from the image file.

FIG. 2 is a block diagram of a configuration of the image sensor 100according to some example embodiments.

Referring to FIG. 2, the image sensor 100 may include the pixel array110, the controller 120, the signal processor 130, a row driver 140, anda signal reader 150. The signal reader 150 may include acorrelated-double sampler (CDS) 151, an analog-digital converter (ADC)153, and a buffer 155.

The pixel array 110 may include a first pixel group PG1 and a secondpixel group PG2. The first pixel group PG1 may include a plurality ofpixels PX11 to PX14, and the second pixel group PG2 may include pixelsPX11 to PX24. The plurality of pixels PX11 through PX24 may generate animage signal based on light 2001 reflected from the object 2000 in FIG.1 and incident on the pixel array 110.

According to some example embodiments, a pixel group may include aplurality of pixels sharing a floating diffusion (FD) node, and thepixel group may be referred to as a shared pixel. For example, the firstpixel group PG1 may include a plurality of pixels PX11 through PX14connected to a first FD node. As another example, the second pixel groupPG2 may include a plurality of pixels PX21 through PX24 connected to asecond FD node, the second FD node being different from the first FDnode.

According to some example embodiments, the first pixel group PG1 and thesecond pixel group PG2 may be adjacent to each other. Referring to FIG.2, the first pixel group PG1 and the second pixel group PG2 may beadjacent to each other in a horizontal direction. However, some exampleembodiments are not limited thereto. The first pixel group PG1 andsecond pixel group PG2 may be adjacent to each other in a verticaldirection.

A plurality of pixel groups may respectively output pixel information tothe CDS 151 through corresponding n column output lines CLO_0 throughCLO_n-1. For example, the first pixel group PG1 may provide a pixelsignal to the CDS 151 through a first column output line CLO_0. Thesecond pixel group PG2 may provide the pixel signal to the CDS 151 via asecond column output line CLO_1.

Each pixel group may include a plurality of pixels. According to someexample embodiments, the first pixel group PG1 and the second pixelgroup PG2 may respectively include four pixels. Each of the plurality ofpixels may include a corresponding photo-sensing element. Thephoto-sensing element may absorb light (e.g., light 2001) and generate acharge in response to the absorbing. For example, the photo-sensingelement may be a photodiode. It will be understood that anyphoto-sensing element as described herein may be a photodiode. The firstpixel group PG1 may include a plurality of photodiodes and the first FDnode. The first FD node may be shared by the plurality of photodiodes.Restated, the first pixel group PG1 may include a plurality of firstphotodiodes (e.g., PX11 to PX14) sharing a first node (first FD node,e.g., ND1 as shown in FIG. 3A) connected to a first capacitor (e.g., C1as shown in FIG. 3A). Like the description of the first pixel group PG1,the second pixel group PG2 may include a plurality of photodiodes and anFD node shared by the plurality of photodiodes. Restated, the secondpixel group PG2 may include a plurality of first photodiodes (e.g., PX21to PX24) sharing a second node (second FD node, e.g., ND2 as shown inFIG. 3A) connected to a second capacitor (e.g., C2 as shown in FIG. 3A).

The controller 120 may control the row driver 140 such that the pixelarray 110 may absorb light 2001 to accumulate charge or temporarilystore the accumulated charge and output an electrical signal accordingto the stored charge to the outside of the pixel array 110. In addition,the controller 120 may control the signal reader 150 such that the pixelarray 110 may measure a level of the pixel signal.

The row driver 140 may generate signals such as reset control signalsRSs, transmission control signals TSs, and selection signals SELSs forcontrolling the pixel array 110 and provide the signals to a pluralityof pixel groups PGs. In some example embodiments, the row driver 140 maydetermine a timing of activating and deactivating the reset controlsignals RSs, the transmission control signals RSs, and the selectionsignals SELSs provided to the plurality of pixel groups based on whethera DCG function is performed or not.

The CDS 151 may sample and hold the pixel signal received from the pixelarray 110. The CDS 151 may double-sample a level of specific noise and alevel according to the pixel signal output a level corresponding to thedifference. In addition, the CDS 151 may receive and compare lampsignals generated from a lamp signal generator 157 and output thecomparison result. The ADC 153 may convert an analog signalcorresponding to a level received from the CDS 151 into a digitalsignal. The buffer 155 may latch the digital signal and the latchedsignal may be sequentially output (e.g., transmitted) to the signalprocessor 130 or the outside of the image sensor 100.

The signal processor 130 may perform a signal processing operation basedon the received pixel signal. For example, the signal processor 130 mayperform a noise reduction processing operation, a gain adjustmentoperation, a waveform shaping processing operation, an interpolationprocessing operation, a white-balance processing operation, a gammaprocessing operation, an edge emphasis processing operation, or thelike.

FIGS. 3A and 3B respectively illustrate a circuit diagram and a layoutof the first pixel group PG1 and the second pixel group PG2.

Hereinafter, the first pixel group PG1 will now be described forconvenience of explanation, but the description of the first pixel groupPG1 may be equally applied to the second pixel group PG2 and other pixelgroups.

The first pixel group PG1 may include a plurality of photo-sensingelements PD11 through PD14, a plurality of transfer transistors TG11through TG14, a selection transistor SG1, a driving transistor DG1, andreset transistors RG11 and RG12.

Each of the plurality of photo-sensing elements PD11 through PD14 maygenerate a photo-charge according to an intensity of the incident light(e.g., light 2001). For example, each of the plurality of photo-sensingelements PD11 through PD14 is a P-N junction diode and may generate acharge, that is, electrons as a negative charge and holes as a positivecharge, in proportion to the amount of received light. Each of theplurality of photo-sensing elements PD11 through PD14 may include, as anexample of photoelectric conversion elements, at least one of aphototransistor, a photo gate, a pinned photo diode (PPD), and acombination thereof.

In some example embodiments, each photo-sensing element of the pluralityof photo-sensing elements PD11 through PD14 (e.g., first photodiodes)includes a first color filter configured to selectively transmit alimited portion of the incident light having a first wavelength spectrumassociated with a first color. In some example embodiments, eachphoto-sensing element of the plurality of photo-sensing elements PD21through PD24 (e.g., second photodiodes) includes a second color filterconfigured to selectively transmit light associated with a limitedportion of the incident light having a second wavelength spectrumassociated with a second color. The first color may be different fromthe second color, and thus the first wavelength spectrum may bedifferent from the second wavelength spectrum.

Each of the plurality of transfer transistors TG11 through TG14 maytransmit the photo-charge generated in the photo-sensing elements PD11through PD14 to a first node ND1, according to the transmission controlsignal TSs in FIG. 2. The first node ND1 may be referred to as a firstfloating diffusion node of the first pixel group PG1 and which is sharedby the photo-sensing elements PD11 through PD14 (e.g., plurality offirst photodiodes). Similarly, the second node ND2 may be referred to asa second floating diffusion node of the second pixel group PG2 and whichis shared by the photo-sensing elements PD21 through PD24 (e.g.,plurality of second photodiodes).

A first capacitor C1 may store the transmitted photo-charge transmittedfrom the plurality of photo-sensing elements PD11 through PD14 throughthe plurality of transfer transistors TG11 through TG14. The firstcapacitor C1 may be connected to the first node ND1 and cause (e.g.,generate) a voltage based on storing the transmitted photo-charge. Whena capacitance value of the first capacitor C1 is small, a small amountof charge may be stored and the magnitude of a voltage change of thefirst node ND1 may also be small. Accordingly, the image sensor 100 mayoperate in the HCG mode when a capacitance value of the first node ND1is small. When the capacitance value of the first capacitor C1 is large,a large amount of charge may be stored and the magnitude of the voltagechange may also be large. Accordingly, the image sensor 100 may operatein the LCG mode when the capacitance value of the first node ND1 islarge.

Similarly to the first capacitor C1, the second capacitor C2 may storethe transmitted photo-charge transmitted from the plurality ofphoto-sensing elements PD21 through PD24 through the plurality oftransfer transistors TG21 through TG24. The second capacitor C2 may beconnected to the second node ND2 and cause (e.g., generate) a voltagebased on storing the transmitted photo-charge.

The driving transistor DG1 may correspond to a buffer amplifier. Thedriving transistor DG1 may be referred to as a source follower (SF).Since a gate of the driving transistor DG1 is connected to the firstnode ND1, a voltage of the first node ND1 may correspond to a gatevoltage of the driving transistor DG1. That is, the driving transistorDG1 may amplify a value of the gate voltage which is changed based onthe photo-charge transmitted to the first node ND1 and output a pixelsignal VOUT1.

The selection transistor SG1 may output the pixel signal VOUT1 to theCDS (for example, 151 in FIG. 2) through the first column output lineCLO_0 by connecting a drain node to a source node of the drivingtransistor DG1 in response to the selection signal (for example, SELSsin FIG. 2).

The first pixel group PG1 may include the first reset transistor RG11and the second reset transistor RG12. The first reset transistor RG11and the second reset transistor RG12 may be connected in series througha third node ND3. The third node ND3 may be connected to a thirdcapacitor C3. When the second reset transistor RG12 is turned on, thefirst node ND1 and the third node ND3 may be connected. Accordingly, thesecond reset transistor RG12 may be configured to selectively connectthe first node ND1 to the third node ND3. When the first resettransistor RG11 is turned on, the third node ND3 and a pixel voltagenode VPIX may be connected. Accordingly, the first reset transistor RG11and the second reset transistor RG21 may each be configured toselectively connect the third node ND3 to the pixel voltage node VPIXand may be configured to reset the third node ND3 to a pixel voltageaccording to an operation of the first reset transistor RG11 and/or thesecond reset transistor RG21.

The first reset transistor RG11 and the second reset transistor RG12 mayperform the DVG operation. Accordingly, the first reset transistor RG11and the second reset transistor RG22 may be collectively configured toselectively electrically connect the first node ND1, the second nodeND2, and the third node ND3 to each other according to an operation ofthe first reset transistor RG11 and the second reset transistor RG22.For example, in a case of the HCG mode, the first reset transistor RG11may be turned on and the second reset transistor RG12 may be turned off.Since the first reset transistor RG11 is turned on, the first resettransistor RG11 may be equivalent to a short circuit. Accordingly, avoltage value of the pixel voltage node VPIX may be transmitted to adrain terminal of the second reset transistor RG12. In the HCG mode,when the second reset transistor RG12 is turned on, the second resettransistor RG12 may be equivalent to a short circuit. Accordingly, thefirst node ND1 may be reset to the voltage value of the pixel voltagenode VPIX sequentially through the second reset transistor RG12 and thefirst reset transistor RG11.

In a case of the LCG mode, the first reset transistor RG11 may be turnedoff and the second reset transistor RG12 may be turned on. Since thesecond reset transistor RG12 is turned on, the second reset transistorRG12 may be equivalent to a short circuit. Meanwhile, since a thirdreset transistor RG21 and a fourth reset transistor RG22 included in thesecond pixel group PG2 respectively operate in a same manner as thefirst reset transistor RG11 and the second reset transistor, the fourthreset transistor RG22 may be short-circuited in the LCG mode.Accordingly, the fourth reset transistor RG22 may be configured toselectively connect the second node ND2 to the third node ND3. Sinceboth the second reset transistor RG12 and the fourth reset transistorRG22 are short-circuited, the first node ND1 and the third node ND3 maybe integrated into one node. Therefore, when viewing the first node ND1or the third node ND3, the first capacitor C1, the second capacitor C2,and the third capacitor C3 may be connected in parallel and a totalcapacitance C1+C2+C3 of the first node ND1 or the third node ND3 may beincreased. When the first reset transistor RG11 is turned on in the LCGmode, charges accumulated in the first node ND1 (or the third node ND3)may be discharged to the pixel voltage node VPIX along the first resettransistor RG11. Herein, the charges accumulated in the first node ND1(or the third node ND3) may be referred to as a sum of charges stored inthe first capacitor C1 to the third capacitor C3.

According to some example embodiments, the image sensor 100 maydynamically set the capacitance value of the floating diffusion node(for example, the first node ND1 of the first pixel group PG1). When theHCG is utilized, for example, when a surrounding luminance is low, theimage sensor 100 may turn on a reset transistor (for example, the firstreset transistor RG11) connected to the pixel voltage node VPIX andcontrol the second reset transistor RG12 to perform a reset operationonly with an FD node having a small capacitance value of the firstcapacitor C1. When the LCG is utilized, for example, when thesurrounding luminance is low, the image sensor 100 may increase thecapacitance value of the FD node to a total sum of capacitances of thefirst capacitor C1 to the third capacitor C3 (e.g., the first capacitorC1, the second capacitor C2, and the third capacitor C3) by turning onthe second reset transistor RG12 and the fourth reset transistor RG22connected to the third node ND3 and perform a reset operation in thefloating diffusion node having a high capacitance value by controllingthe first reset transistor RG11.

Referring to FIG. 3B, a layout implementing the circuit diagram of FIG.3A is shown. Hereinafter, for convenience of explanation, the pixelvoltage node VPIX connected to drain nodes of the transfer transistorsTG11 through TG24, the driving transistors DG1 and DG2, the selectiontransistors SG1 and SG2, and the driving transistors DG1 and DG2 may beshown as omitted.

The first pixel group PG1 and the second pixel group PG2 supporting theDCG may respectively include four pixels PD11 through PD14 and PD21through PD24, and the first pixel group PG1 may be adjacent to thesecond pixel group PG2.

Four reset transistors RG11 through RG22 and six metal contacts may beformed in the first pixel group PG1 and the second pixel group PG2. Indetail, the six metal contacts may include a metal contact connected tothe first capacitor C1 at the first node ND1, a metal contact connectedto the second capacitor C2 at the second node ND2, two metal contactssimultaneously connected to the first node ND1 of the first pixel groupPG1 and the second node ND2 of the second pixel group PG2 from the thirdnode ND3 with the third capacitor C3, and two metal contactsrespectively connected to the pixel voltage nodes VPIXs in the firstreset transistor RG11 and the third reset transistor RG21.

The image sensor 100 may connect the first node ND1, the second nodeND2, and the third node ND3 to one node by turning on andshort-circuiting the second reset transistor RG12 and the fourth resettransistor RG22. Therefore, the capacitance value of the floatingdiffusion node of the first pixel group PG1 may increase.

When the size of a pixel is relatively large compared to the metalcontact, arranging the first to third capacitors C1 through C3 and themetal contacts between the first pixel group PG1 and the second pixelgroup PG2 adjacent to the first pixel group PG1 may be easy. However,when the size of the pixel is relatively small according to theminiaturization of the size of the pixel and the size of the metalcontact is relatively increased, arranging the first to third capacitorsC1 through C3 with the metal contacts while satisfying a design rule maybe difficult.

Therefore, a layout using a reduced number of transistors and metalcontacts while supporting the same DCG may be implemented. This will bedescribed later reference to FIGS. 4 to 10B.

FIG. 4 is a circuit diagram in which the first pixel group PG1 and thesecond pixel group PG2 share transistors and voltage nodes according tosome example embodiments. Hereinafter, descriptions previously givenabove are omitted.

Referring to FIG. 4, the first reset transistor RG11 and the third resettransistor RG21 of FIG. 3A may be replaced by one transistor: sharedreset transistor RG1, also referred to herein as a common transistor,which may be a common transistor configured to reset the third node ND3to a pixel voltage according to an operation of the common transistor.

The first reset transistor RG11 and the third reset transistor RG21 inFIG. 3A may be replaced with one transistor, shared reset transistorRG1, since the first reset transistor RG11 and the third resettransistor RG21 are turned on or turned off in response to a resetcontrol signal (for example, RSs) at a same timing. In addition, sincethe pixel voltage node VPIX connected to the first reset transistor RG11and the pixel voltage node VPIX connected to the third reset transistorRG21 in FIG. 3A are common, the two pixel voltage nodes VPIX may bereplaced by one pixel voltage node VPIX.

Therefore, referring to FIGS. 3A, 3B, and 4 together, the number (e.g.,quantity) of transistors used may be reduced by one and the number ofmetal contacts connected to the pixel voltage node may also be reducedby one by sharing the first reset transistor RG11 of the first pixelgroup PG1 and the third reset transistor RG21 of the second pixel groupas one reset transistor, shared reset transistor RG1, and connecting thepixel voltage node VPIX.

Although the first pixel group PG1 is shown as including fourphoto-sensing elements PD11 through PD14 and four transfer transistorsTG11 through TG14 in the drawings, the inventive concepts are notlimited thereto. The number (e.g., quantity) of photo-sensing elementsand the number of transfer transistors included in the first pixel groupPG1 may vary according to some example embodiments to maintain anappropriate balance between an area gain, which may be obtained as thenumber of floating diffusion nodes shared increases, and a read speed,which may be reduced.

In some example embodiments, the image sensor 100 may be configured toturn on the shared reset transistor RG1, and turn off both the secondand fourth reset transistors RG12 and RG22, to set a first conversiongain of the photo-sensing elements PD11 through PD14 based on the firstcapacitor C1, and set second conversion gain of the photo-sensingelements PD21 through PD24 based on the second capacitor C2. In someexample embodiments, the image sensor 100 may be configured to turn offthe shared reset transistor RG1, and turn on both the second and fourthreset transistors RG12 and RG22, to set each of a first conversion gainof the photo-sensing elements PD11 through PD14 and a second conversiongain of the photo-sensing elements PD21 through PD24 based on the firstcapacitor C1, the second capacitor C2, and the third capacitor C3.

FIGS. 5A and 5B respectively illustrate a circuit diagram and a layoutin which a 3-way transistor RG3 is used according to some exampleembodiments. Hereinafter, descriptions previously given above areomitted.

Referring to FIGS. 4 and 5A, the second reset transistor RG12 and thefourth reset transistor RG22 may be replaced with (e.g., may becollectively comprised by) a 3-way transistor RG3. The 3-way transistorRG3 may include three terminals, and each terminal of the threeterminals may be connected (e.g., directly connected) to a separate oneof the first node ND1, the second node ND2, and the third node ND3. The3-way transistor RG3 may generate an electrical connection between thefirst node ND1 to the third node ND3 based on the reset control signalsRSs. For example, when the 3-way transistor RG3 is turned on, the firstnode ND1, the second node ND2, and the third node ND3 may beelectrically connected to each other to be equivalent to one node.

According to some example embodiments, the image sensor 100 may supportthe LCG mode by controlling the 3-way transistor RG3 and a shared resettransistor RG1 (also referred to herein as a common transistor). Forexample, the image sensor 100 may turn off the shared reset transistorRG1 and turn on the 3-way transistor RG3 to support the LCG mode. Whenthe 3-way transistor RG3 is turned on, the first node ND1 to the thirdnode ND3 are connected to each other to operate as one node and thefirst capacitor C1 to the third capacitor C3 respectively connected tothe first node ND1 to the third node ND3 may be connected in parallel.Therefore, a value of capacitance viewed from the first floatingdiffusion node (that is, the first node ND1) of the first pixel groupPG1 may be increased.

According to some example embodiments, the image sensor 100 may supportthe HCG mode by controlling the 3-way transistor RG3 and the sharedreset transistor RG1. For example, the image sensor 100 may turn on theshared reset transistor RG1 and turn off the 3-way transistor RG3 tosupport the HCG mode. The shared reset transistor RG1 may selectivelyconnect the third node ND3 to the pixel voltage node VPIX. When theshared reset transistor RG1 is turned on, which is equivalent to a shortcircuit, a voltage of a terminal connected to the third node ND3 of the3-way transistor RG3 may be set to a voltage value of the pixel voltagenode VPIX. Thereafter, when the 3-way transistor RG3 is turned on,photo-charges stored in the first node ND1 of the first pixel group PG1may be discharged through the shared reset transistor RG1 and the pixelvoltage node VPIX. A capacitance value of the first pixel group PG1 maycorrespond to a capacitance value of the first capacitor C1. A resetoperation of the first pixel group PG1 may be equally applied to a resetoperation of the second pixel group PG2.

Referring to FIG. 5B, a layout implementing the circuit diagram of FIG.5A is shown. Hereinafter, for convenience of explanation, the pixelvoltage node VPIX connected to the drain nodes of the transfertransistors TG11 through TG24, the driving transistors DG1 and DG2, theselection transistors SG1 and SG2, and the driving transistors DG1 andDG2 may be shown as omitted.

Referring to FIGS. 3B and 5B together, two reset transistors and fourmetal contacts may be formed in the first pixel group PG1 and the secondpixel group PG2. The two reset transistors may include the shared resettransistor RG1 and the 3-way transistor RG3. The four metal contacts mayinclude a first metal contact MC1 arranging the first capacitor C1 atthe first node and connecting (e.g., directly connecting) the firstcapacitor C1 to the 3-way transistor RG3, a second metal contact MC2arranging the second capacitor C2 at the second node ND2 and connecting(e.g., directly connecting) the second capacitor C2 to the 3-waytransistor RG3, a third metal contact MC3 arranging the third capacitorC3 at the third node ND3 and connecting (e.g., directly connecting) thethird capacitor C3 to the 3-way transistor RG3, and a fourth metalcontact MC4 connecting (e.g., directly connecting) the shared resettransistor RG1 to the pixel voltage node VPIX. As shown in FIG. 5B, thefirst metal contact MC1 and the second metal contact MC2 may be alignedin a horizontal direction, and the third metal contact MC3 and thefourth metal contact MC4 may be aligned in a vertical direction. Asshown in FIG. 5B, a center of the third metal contact MC3 and the fourthmetal contact MC4 may have a concave-convex shape ⊥ isolated from directcontact with a center of the first metal contact MC1 and the secondmetal contact MC2 in the vertical direction.

According to some example embodiments and comparing FIGS. 4 and 5B, thenumber (e.g., quantity) of transistors used may be reduced by one byreplacing the second reset transistor RG12 and the fourth resettransistor RG22 with the 3-way transistor RG3. In addition, the thirdcapacitor C3 may utilize two metal contacts to be respectively connectedto the first node ND1 and the second node ND2 in FIG. 4, but one metalcontact may be additionally reduced by connecting the third capacitor C3only to the third node ND3 in FIG. 5B.

FIGS. 6A and 6B respectively illustrate a circuit diagram and a layoutin which a 4-way transistor RG4 is used according to some exampleembodiments. Hereinafter, descriptions previously given above areomitted.

Referring to FIGS. 5A and 6A, the 3-way transistor RG3 of FIG. 5A may bereplaced with (e.g., may be collectively comprised by) the 4-waytransistor RG4. The 4-way transistor RG4 may include four terminals, andeach terminal of the four terminals may be connected (e.g., directlyconnected) to a separate one of the first node ND1, the second node ND2,the third node ND3, and the third capacitor C3. The 4-way transistor RG4may be connected to the first pixel group PG1 through the first nodeND1, may be connected to the second pixel group PG2 through the secondnode ND2, and may be connected to the shared reset transistor (e.g.,shared reset transistor RG1) and the pixel voltage node VPIX through thethird node ND3. Restated, the terminal directly connected to the thirdnode may be connected to the shared reset transistor RG1 via the thirdnode ND3.

According to some example embodiments, referring to FIG. 5A, the thirdcapacitor C3 connected in parallel to the third node ND3 may berearranged to be connected to another terminal except for the terminalsconnected to the first node ND1 to the third node ND3 of the 4-waytransistor RG4. A space between the first pixel group PG1 and the secondpixel group PG2 may be efficiently used by rearranging the thirdcapacitor C3.

Referring to FIG. 6B, a layout implementing the circuit diagram of FIG.6A is shown. Hereinafter, for convenience of explanation, the pixelvoltage node VPIX connected to the drain nodes of the transfertransistors TG11 through TG24, the driving transistors DG1 and DG2, theselection transistors SG1 and SG2, and the driving transistors DG1 andDG2 may be shown as omitted.

Referring to FIGS. 5B and 6B together, two reset transistors and fourmetal contacts may be formed in the first pixel group PG1 and the secondpixel group PG2. The two reset transistors may include the shared resettransistor RG1 and the 4-way transistor RG4. The four metal contacts mayinclude three metal contacts forming an electrical connection from the4-way transistor RG4 to the first capacitor C1 through the thirdcapacitor C3, (e.g., a first metal contact MC1 connecting the firstcapacitor C1 to the 4-way transistor RG4, a second metal contact MC2connecting the second capacitor C2 to the 4-way transistor RG4, and athird metal contact MC3 connecting the third capacitor to the 4-waytransistor RG4) and one metal contact (e.g., fourth metal contact MC4)connecting the shared reset transistor RG1 to the pixel voltage nodeVPIX.

According to some example embodiments and comparing FIGS. 5B and 6B, thenumber (“quantity”) of transistors and the number of metal contacts maybe the same. However, a concave-convex shape ⊥ defined by the metalcontacts may be changed into a cross shape

based on rearranging the third metal contact MC3 connected to the thirdcapacitor C3 to be connected (e.g., directly connected) to a lowerterminal of the 4-way transistor RG4. As shown in FIG. 6B, the firstmetal contact MC1 and the second metal contact MC2 may be aligned in ahorizontal direction, and the third metal contact MC3 and the fourthmetal contact MC4 may be aligned in a vertical direction, and a centerof the third metal contact MC3 and the fourth metal contact MC4 may beformed to have a cross shape

in conformity with a center of the first metal contact MC1 and thesecond metal contact MC1. As a result, space efficiency may be increasedand a layout complexity of the image sensor supporting the DCG functionmay be reduced by arranging two metal contacts in a vertical direction(e.g., MC3 and MC4) and two metal contacts in a horizontal direction(e.g., MC1 and MC2) to intersect with each other, as shown in at leastFIG. 6B.

FIGS. 7A and 7B respectively illustrate a circuit diagram and a layoutin which an additional (fourth) capacitor is connected to the 4-waytransistor RG4 according to some example embodiments. Hereinafter,descriptions previously given above are omitted.

Referring to FIGS. 6A and 7A, the third node ND3 may further include afourth capacitor C4. In FIG. 6A, the third node ND3 merely electricallyconnects the shared reset transistor RG1 and the 4-way transistor RG4,but the third node ND3 may further include the fourth capacitor C4 inFIG. 7A. As shown, the fourth capacitor C4 may be connected in parallelbetween the 4-way transistor RG4 and the shared reset transistor RG1.

According to some example embodiments, the image sensor 100 may supportan LCG mode with a lower conversion gain. For example, referring to FIG.6A, a total capacitance value may correspond to the sum of thecapacitances of the first capacitor C1 to the third capacitor C3 evenwhen the 4-way transistor RG4 is turned on and the first node ND1 to thethird node ND3 connect to one node. In some example embodiments,referring to FIG. 7A, when the 4-way transistor RG4 is turned on and theshared reset transistor RG1 is turned off, a total capacitance viewedfrom the first pixel group PG1 may correspond to a sum of thecapacitance of the first capacitor C1 of the first node ND1, the secondcapacitor C2 of the second node ND2 connected in parallel through the4-way transistor RG4, the third capacitor C3 connected in parallelthrough the 4-way transistor RG4, and the fourth capacitor CG4 added tothe third node ND3. Accordingly, since the value of the totalcapacitance viewed from the first pixel group PG1 has increased, the LCGmode with a lower conversion gain may be performed.

Referring to FIG. 7B, two reset transistors and five metal contacts maybe formed in the first pixel group PG1 and the second pixel group PG2.The five metal contacts may further include, in addition to three metalcontacts forming an electrical connection from the 4-way transistor RG4to the first capacitor C1 through the third capacitor C3 and one metalcontact connecting the shared reset transistor RG1 to the pixel voltagenode VPIX, one metal contact forming an electrical connection from the4-way transistor RG4 to the fourth capacitor C4.

According to some example embodiments and comparing FIGS. 6B and 7B,since the LCG mode with the lower conversion gain may be operated thoughthe number of metal contacts may be increased, the image sensor 100 mayimprove object recognition ability in light of a brighter intensity.

FIGS. 8A and 8B respectively illustrate a circuit diagram in which thefirst pixel group PG1 and the second pixel group PG2 share transistorsand voltage nodes. Hereinafter, descriptions previously given above areomitted.

Referring to FIG. 8A, the second reset transistor RG12 and the fourthtransistor RG22 may be connected in series. In FIG. 4, the second resettransistor RG12 and the fourth transistor RG22 may be connected inparallel with respect to the third node ND3. In some exampleembodiments, in FIG. 8A, a source terminal of the second resettransistor RG12 may be connected to the first node ND1 and a drainterminal of the second reset transistor RG12 may be connected to asource terminal of the fourth reset transistor RG22 or to the secondnode ND2. Accordingly, the second reset transistor RG12 may beconfigured to selectively connect the first node ND1 to the second nodeND2. A drain terminal of the fourth reset transistor RG22 may beconnected in parallel to a source terminal of the shared resettransistor RG1 and the third capacitor C3. Accordingly, the fourth resettransistor RG22 may be configured to selectively connect the second nodeND2 to the third node ND3. As shown in FIG. 8A, the shared resettransistor RG1 may be configured to selectively connect the third nodeMD3 to the pixel voltage node VPIX. As shown in FIG. 8A, the third nodeincludes an electrical connection with the third capacitor C3.

FIG. 8B shows a layout implementing the circuit diagram of FIG. 8AHereinafter, for convenience of explanation, the pixel voltage node VPIXconnected to the drain nodes of the transfer transistors TG11 throughTG24, the driving transistors DG1 and DG2, the selection transistors SG1and SG2, and the driving transistors DG1 and DG2 may be shown asomitted.

Referring to FIG. 8B, the metal contacts may be arranged in series. Forexample, a metal contact connecting the pixel voltage node VPIX to theshared reset transistor RG1, a metal contact connecting the thirdcapacitor C3 to the third node ND3, a metal contact connecting thesecond capacitor C2 to the second node ND2, and a metal contactconnecting the first capacitor C1 to the first node may be sequentiallyarranged in the vertical direction. Accordingly, the image sensor 100may be configured to turn on the shared reset transistor RG1, the secondreset transistor RG12, and the fourth reset transistor RG22 to establishan electrical connection in series according to a sequence of the pixelvoltage node VPIX, the third capacitor C3, the second node ND2, and thefirst node ND1.

According to some example embodiments, the number of transistorsarranged between the first pixel group PG1 and the pixel voltage nodeVPIX may be different from the number of transistors arranged betweenthe second pixel group PG2 and the pixel voltage node VPIX. For example,the second reset transistor RG12, the fourth reset transistor RG22, andthe shared reset transistor RG1, that is, three transistors may bearranged between the first pixel group PG1 and the pixel voltage nodeVPIX. As another example, the fourth reset transistor RG22 and theshared reset transistor RG1, that is, two transistors may be arrangedbetween the second pixel group PG2 and the pixel voltage node VPIX.Accordingly, a number (e.g., quantity) of reset transistors between thefirst node ND1 and the pixel voltage node VPIX may be different from anumber (e.g., quantity) of reset transistors between the second node ND2and the pixel voltage node VPIX. A difference in the number oftransistors from a neighboring pixel group to the pixel voltage nodeVPIX may be because the second reset transistor RG12 and the fourthreset transistor RG22 are connected in series.

According to some example embodiments, the metal contacts may bearranged along a straight line in the vertical direction without beingarranged in the concave-convex shape ⊥ or the cross shape

. When the size of a pixel is relatively large compared to the metalcontacts, an arrangement according to the concave-convex shape ⊥ or thecross shape

shown in FIGS. 4 to 7B may not be difficult. However, when the size ofthe pixel is reduced due to a fine operation and miniaturization (forexample, a tetra-cell), an arrangement of a metal contact between twopixels (for example, PD11 and PD12 or PD13 and PD14), which are inparallel in the horizontal direction, may be difficult. Thus, asdescribed above, forming a metal contact between two pixels which are inparallel in the horizontal direction in one pixel group may be avoidedand the size of the pixel may be miniaturized (e.g., reduced and/orminimized) based on connecting the second reset transistor TG12 to thefourth reset transistor RG22 in series and arranging the capacitorsbetween the transistors.

FIGS. 9A and 9B respectively illustrate a circuit diagram in which thefirst pixel group PG1 and the second pixel group PG2 share transistorsand voltage nodes according to some example embodiments. Hereinafter,descriptions previously given above are omitted.

Referring to FIGS. 8A and 9A together, the first node ND1 of the firstreset transistor PG1 may further include a fifth reset transistor RG5connected in parallel. Restated, the fifth reset transistor RG5 may beconnected in parallel to the first node ND1. The third capacitor C3arranged between the shared reset transistor RG1 and in fourth resettransistor RG22 in FIG. 8A may be rearranged to be connected to thefifth reset transistor RG5.

Referring to FIGS. 8B and 9B, since the fifth reset transistor RG5 isadded to rearrange the third capacitor C3, four transistors and fourmetal contacts may be formed in the first pixel group PG1 and the secondpixel group PG2.

FIGS. 10A and 10B respectively illustrate a circuit diagram and a layoutin which an additional capacitor is connected according to some exampleembodiments. Hereinafter, descriptions previously given above areomitted.

Referring to FIGS. 9A and 10A together, the third node ND3 may furtherinclude the third node ND3. In FIG. 9A, the third node ND3 merelyelectrically connects the shared reset transistor RG1 and the fourthreset transistor RG22 of the second pixel group PG2, but the third nodeND3 in FIG. 10A may further include the fourth capacitor C4 connected inparallel. The fifth reset transistor RG5 may be configured toselectively connect the first node ND1 to the fourth capacitor C4.

According to some example embodiments, the image sensor 100 may supportthe LCG mode with the lower conversion gain. A sum of capacitance viewedfrom the first node ND1 of the first pixel group PG1 may be equal to asum of the capacitances of the first capacitor C1 to the fourthcapacitor C4. In some example embodiments, the image sensor 100 isconfigured to turn off the shared reset transistor RG1 and turn on boththe second reset transistor RG22 and the fourth reset transistor RG12 toset each of a first conversion gain of the first photo-sensing elementsPD11 to PD14 and a second conversion gain of the second photo-sensingelements PD21 to PD24 based on the first capacitor C1, the secondcapacitor C2, the third capacitor C3, and the fourth capacitor C4.Thereafter, a detailed description with respect to the LCG mode with thelower conversion gain may be replaced with the description of FIG. 7B.

Referring to FIGS. 9B and 10B together, four transistors and five metalcontacts may be formed in the first pixel group PG1 and the second pixelgroup PG2. Comparing with FIG. 9B, one metal contact may be additionallyimplemented in FIG. 10B. The added metal contact may correspond to ametal contact arranging the fourth capacitor C4 connected in parallel tothe third node ND3 between the shared reset transistor RG1 and thefourth reset transistor RG22. According to some example embodiments, thefour transistors and the five metal contacts may be connected in seriesto intersect.

According to the above-mentioned FIGS. 4 to 10B, the transistors andshared reset transistors being between the first pixel group PG1 and thesecond pixel group PG2 are disclosed in some example embodiments.According to some example embodiments, the DCG may be supported by usingfewer transistors and metal contacts between neighboring pixel groups.In addition, the number of transistors and metal contacts is reduced,thereby reducing the layout complexity and increasing the spaceefficiency. For example, sizes of the driving transistors DG1 and DG2may be increased by using a space obtained by saving the transistors andmetal contacts. When the sizes of the driving transistors DG1 and DG2are increased, a random telegraph signal (RTS) noise may be improved andrandom noise may also be improved. In addition, when the sizes of thedriving transistors DG1 and DG2 are increased, linearity is increased.As shown in FIGS. 10A-10B, a number (e.g., quantity) of resettransistors between the third capacitor C3 and the pixel voltage nodeVPIX (e.g., four reset transistors) may be different from a number(e.g., quantity) of reset transistors between the fourth capacitor C4and the pixel voltage node VPIX (e.g., one reset transistor).

FIG. 11 is a block diagram of a computing system 3000 including an imagesensor 3600 according to some example embodiments.

Referring to FIG. 11, the computing system 3000 may include an imageprocessor 3100, a memory device 3200, a storage device 3300, aninput/output device 3400, a power supply 3500, and the image sensor3600. The image sensor 3600 may include the image sensor according tosome example embodiments of the inventive concepts described above withreference to FIGS. 1 to 16. Although not illustrated in FIG. 11, thecomputing system 3000 a port which may communicate with a video card, asound card, a memory card, a USB device, or the like or may communicatewith other electronic devices.

The image processor 3100 may perform certain calculations or tasks. Theimage processor 3100 may process signals output from the image sensor3600 according to some example embodiments of the inventive conceptsdescribed above with respect to FIGS. 1 to 10B and may control anoperation of the image sensor 3600. For example, the image sensor 3600may determine to operate in the HCG mode or the LCG mode depending on asurrounding luminance. Accordingly, an image having an optimalresolution may be obtained (e.g., generated) irrespective of differentilluminant environments. The image processor 3100 may include processingcircuitry such as hardware including logic circuits; a hardware/softwarecombination such as a processor executing software; or a combinationthereof. For example, the processing circuitry more specifically mayinclude, but is not limited to, a central processing unit (CPU), anarithmetic logic unit (ALU), a digital signal processor, amicrocomputer, a field programmable gate array (FPGA), a System-on-Chip(SoC), a programmable logic unit, a microprocessor, application-specificintegrated circuit (ASIC), etc.

The memory device 3200 may be a non-transitory computer-readable storagedevice that may store data necessary for an operation of the computingsystem 3000. For example, the memory device 3200 may include a dynamicrandom access memory (DRAM), a mobile DRAM, a static random accessmemory (SRAM), or a non-volatile memory device. Chips of the memoriesmay be implemented by using various types of packages, eitherindividually or together. For example, the chips may be packaged as apackage such as a package on package (PoP), ball grid arrays (BGAs),chip scale packages (CSPs), a plastic leaded chip carrier (PLCC), aplastic dual in-line package (PDIP), a die in waffle pack, a die inwafer form, a chip on board (COB), a ceramic dual in-line package(CERDIP), a plastic metric quad flat pack (MQFP), or the like. In someexample embodiments, the memory device 3200 may store a program ofinstructions and the image processor 3100 may be configured to executethe program of instructions to implement some or all of thefunctionality of the computing system 3000.

The storage device 3300 may include a solid state drive (SSD), a harddisk drive (HDD), a CD-ROM, or the like. The input/output device 3400may include input measures and output units, the input measuresincluding a keyboard, a keypad, a mouse, or the like, and the outputunits including a printer, a display, or the like. The power supply 3500may supply an operating voltage utilized for an operation of thecomputing system 3000.

The image sensor 3600 may connect to the image processor 3100 throughbuses or other communication links to perform communications. The imagesensor 3600 may be integrated on one chip together with the imageprocessor 3100 or may be integrated on different chips. Meanwhile, thecomputing system 3000 should be interpreted as any computing systemusing an image sensor. For example, the computing system may include adigital camera, a mobile phone, a personal digital assistant (PDA), aportable multimedia player (PMP), a smartphone, a tablet PC, or thelike.

As described above, some example embodiments have been disclosed in thedrawings and disclosure. Although specific language has been used todescribe some example embodiments in the inventive concepts, thespecific language is used for the purpose of describing the spirit ofthe inventive concepts and no limitation of the scope of the inventiveconcepts as defined by the following claims is intended by this specificlanguage. While the inventive concepts have been particularly shown anddescribed with reference to some example embodiments thereof, it will beunderstood that various changes in form and details may be made thereinwithout departing from the spirit and scope of the following claims.

What is claimed is:
 1. An image sensor, comprising: a plurality of firstphotodiodes sharing a first floating diffusion node; a plurality ofsecond photodiodes sharing a second floating diffusion node; a commontransistor configured to selectively connect a third floating diffusionnode to a pixel voltage node; a first reset transistor configured toselectively connect the first floating diffusion node to the thirdfloating diffusion node; a second reset transistor configured toselectively connect the second floating diffusion node to the thirdfloating diffusion node; a first driving transistor, the first drivingtransistor having a first source node, the first driving transistorhaving a first gate end that is connected to the first floatingdiffusion node; a second driving transistor, the second drivingtransistor having a second source node, the second driving transistorhaving a second gate end that is connected to the second floatingdiffusion node; a first selection transistor, the first selectiontransistor having a first drain end that is connected to the firstsource node of the first driving transistor; and a second selectiontransistor, the second selection transistor having a second drain endthat is connected to the second source node of the second drivingtransistor.
 2. The image sensor of claim 1, wherein the image sensor isconfigured to turn on the common transistor and turn off both the firstreset transistor and the second reset transistor, to set a firstconversion gain of the plurality of first photodiodes based on a firstcapacitance of the first floating diffusion node, and set a secondconversion gain of the plurality of second photodiodes based on a secondcapacitance of the second floating diffusion node.
 3. The image sensorof claim 1, wherein the image sensor is configured to turn off thecommon transistor and turn on both the first reset transistor and thesecond reset transistor to set each of a first conversion gain of theplurality of first photodiodes and a second conversion gain of theplurality of second photodiodes based on a first capacitance of thefirst floating diffusion node, a second capacitance of the secondfloating diffusion node, and a third capacitance of the third floatingdiffusion node.
 4. The image sensor of claim 1, wherein the first resettransistor and the second reset transistor are collectively comprised byone 3-way transistor, the 3-way transistor including three terminals,each terminal of the three terminals directly connected to a separateone of the first floating diffusion node, the second floating diffusionnode, and the third floating diffusion node.
 5. The image sensor ofclaim 4, further comprising: a first metal contact connecting the firstfloating diffusion node to the 3-way transistor; a second metal contactconnecting the second floating diffusion node to the 3-way transistor; athird metal contact connecting the third floating diffusion node to the3-way transistor; and a fourth metal contact connecting the pixelvoltage node to the common transistor, wherein the first metal contactand the second metal contact are aligned in a horizontal direction,wherein the third metal contact and the fourth metal contact are alignedin a vertical direction, and wherein a center of the third metal contactand a center of the fourth metal contact are each formed to have aconcave-convex shape isolated from direct contact with a center of thefirst metal contact and a center the second metal contact, respectively,in the vertical direction.
 6. The image sensor of claim 1, wherein thefirst reset transistor and the second reset transistor are collectivelycomprised by one 4-way transistor, the 4-way transistor including fourterminals, each terminal of the four terminals directly connected to aseparate one of the first floating diffusion node, the second floatingdiffusion node, the third floating diffusion node, and a firstcapacitor, the terminal directly connected to the third floatingdiffusion node further connected to the common transistor via the thirdfloating diffusion node.
 7. The image sensor of claim 6, furthercomprising: a second capacitor connected in parallel between the 4-waytransistor and the common transistor.
 8. The image sensor of claim 6,further comprising: a first metal contact connecting the first floatingdiffusion node to the 4-way transistor; a second metal contactconnecting the second floating diffusion node to the 4-way transistor; athird metal contact connecting the third floating diffusion node to the4-way transistor; and a fourth metal contact connecting the pixelvoltage node to the common transistor, wherein the first metal contactand the second metal contact are arranged in a horizontal direction,wherein the third metal contact and the fourth metal contact arearranged in a vertical direction, and wherein a center of the thirdmetal contact and a center of the fourth metal contact are each formedto have a cross shape in conformity with a center of the first metalcontact and a center of the second metal contact, respectively.
 9. Animage sensor, comprising: a plurality of first photodiodes sharing afirst floating diffusion node; a plurality of second photodiodes sharinga second floating diffusion node; a first reset transistor configured toselectively connect the first floating diffusion node to the secondfloating diffusion node; a second reset transistor configured toselectively connect the second floating diffusion node to a thirdfloating diffusion node; a common transistor configured to selectivelyconnect the third floating diffusion node to a pixel voltage node; afirst driving transistor, the first driving transistor having a firstsource node, the first driving transistor having a first gate end thatis connected to the first floating diffusion node; a second drivingtransistor, the second driving transistor having a second source node,the second driving transistor having a second gate end that is connectedto the second floating diffusion node; a first selection transistor, thefirst selection transistor having a first drain end that is connected tothe first source node of the first driving transistor; and a secondselection transistor, the second selection transistor having a seconddrain end that is connected to the second source node of the seconddriving transistor.
 10. The image sensor of claim 9, wherein the imagesensor is configured to turn on the common transistor, the first resettransistor, and the second reset transistor to establish an electricalconnection in series according to a sequence of the pixel voltage node,the third floating diffusion node, the second floating diffusion node,and the first floating diffusion node.
 11. The image sensor of claim 9,wherein, a quantity of reset transistors between the first floatingdiffusion node and the pixel voltage node is different from a quantityof reset transistors between the second floating diffusion node and thepixel voltage node.
 12. The image sensor of claim 9, further comprising:a third reset transistor connected in parallel to the first floatingdiffusion node, wherein a capacitor is connected to the third resettransistor.
 13. The image sensor of claim 9, further comprising: a thirdreset transistor connected in parallel to the first floating diffusionnode; and a capacitor, wherein the third reset transistor is configuredto selectively connect the first floating diffusion node to thecapacitor.
 14. The image sensor of claim 13, wherein the image sensor isconfigured to turn off the common transistor and turn on both the firstreset transistor and the third reset transistor, to set each of a firstconversion gain of the plurality of first photodiodes and a secondconversion gain of the plurality of second photodiodes based on a firstcapacitance of the first floating diffusion node, a second capacitanceof the second floating diffusion node, a third capacitance of the thirdfloating diffusion node, and the capacitor.
 15. The image sensor ofclaim 13, wherein a quantity of reset transistors between the thirdfloating diffusion node and the pixel voltage node is different from anumber of reset transistors between the capacitor and the pixel voltagenode.
 16. The image sensor of claim 9, wherein each first photodiode ofthe plurality of first photodiodes includes a first color filterconfigured to selectively transmit light associated with a first color,each second photodiode of the plurality of second photodiodes includes asecond color filter configured to selectively transmit light associatedwith a second color, and the first color is different from the secondcolor.
 17. An electronic device, comprising: an image sensor, the imagesensor including a plurality of first photodiodes sharing a firstfloating diffusion node; a plurality of second photodiodes sharing asecond floating diffusion node; a common transistor configured toselectively connect a third floating diffusion node to a pixel voltagenode; a first reset transistor configured to selectively connect thefirst floating diffusion node to the third floating diffusion node; anda second reset transistor configured to selectively connect the secondfloating diffusion node to the third floating diffusion node; a firstdriving transistor, the first driving transistor having a first sourcenode, the first driving transistor having a first gate end that isconnected to the first floating diffusion node; a second drivingtransistor, the second driving transistor having a second source node,the second driving transistor having a second gate end that is connectedto the second floating diffusion node; a first selection transistor, thefirst selection transistor having a first drain end that is connected tothe first source node of the first driving transistor; and a secondselection transistor, the second selection transistor having a seconddrain end that is connected to the second source node of the seconddriving transistor.
 18. The electronic device of claim 17, wherein thefirst reset transistor and the second reset transistor are collectivelycomprised by one 3-way transistor, the 3-way transistor including threeterminals, each terminal of the three terminals directly connected to aseparate one of the first floating diffusion node, the second floatingdiffusion node, and the third floating diffusion node.
 19. Theelectronic device of claim 17, wherein the first reset transistor andthe second reset transistor are collectively comprised by one 4-waytransistor, the 4-way transistor including four terminals, each terminalof the four terminals directly connected to a separate one of the firstfloating diffusion node, the second floating diffusion node, the thirdfloating diffusion node, and a first capacitor, the terminal directlyconnected to the third floating diffusion node further connected to thecommon transistor via the third floating diffusion node.
 20. Theelectronic device of claim 19, the image sensor further comprising: asecond capacitor connected in parallel between the 4-way transistor andthe common transistor.